The invention relates to a gas bag cover for a vehicle occupant restraint system, comprising a burst line grooved into the cover from the inner side.
Tests have demonstrated that upon bursting of the gas bag cover stress concentrations may occur not only at the initial point but also at other locations. More particularly, if a structure has been applied to the outer side of the cover, for instance a depression or holes for securing a logo badge, the notch effect of these structures results in increased stresses. In this case, there is the risk of the cover not bursting along the provided burst line beginning at the initial point, but at just this location of maximum stress, i.e. for example in the region of an existing badge. This results in the gas bag not deploying as intended and thus in detrimenting proper functioning of the occupant restraint system. Apart from this a danger may arise in the badge releasing from the cover, constituting an additional risk of injury.
The invention provides a gas bag cover which on deployment of the gas bag begins to burst at a precisely predefined point.
For this purpose, a gas bag cover for a vehicle occupant restraint system, having an inner side facing a gas bag to be covered and a wall thickness, comprises at least one burst line being grooved into the cover from the inner side up to a predefined remaining wall thickness, the burst line comprising an initial point at which the remaining wall thickness has its minimum, and the gas bag cover further comprises reinforcement ribs formed on the inner side of the cover, the reinforcement ribs extending along a line which is tangent to the initial point. This assures that the stresses are directed in the cover to the initial point where the bursting action precisely commences.
In accordance with one embodiment of the invention the gas bag cover comprises a badge which is applied to said cover, with the reinforcement ribs running around this badge. Thus a stress concentration in the region of the badge resulting in the cover bursting there is avoided.